The present invention relates to a procedure for the transmission of a subscriber number as defined in the preamble of claim 1. In particular, the invention relates to a procedure for selecting the number or numbers to be transmitted to a subscriber line separately for each subscriber from among possible subscriber numbers received into the telephone exchange system.
In a digital telephone network, such as an ISDN network (ISDN, Integrated Services Digital Network), to allow identification of the parties to a call, it is possible to transmit to a subscriber line the subscriber number or several subscriber numbers of the other party between telephone exchange systems. Typically, the subscriber number transmitted to a subscriber line is the subscriber""s directory number stored e.g. in conjunction with the subscriber data or subscriber line data in a data storage in the telephone exchange system. In a special case, one or the numbers to be transmitted may be a subscriber number provided from the subscriber line, which is not checked by the telephone exchange system. The subscriber holding a subscriber line can decide about the transmission of the subscriber number separately for each subscriber number or subscriber line.
Among previously known number display services allowing the transmission of more than one subscriber number are Calling Line Identification Presentation (CLIP) and Connected Line Presentation (COLP) Essential additional features associated with these services are Calling Line Identification Restriction (CLIR) and Connected Line Presentation Restriction (COLR), respectively.
For example, the service relating to the presentation of the calling number is defined in the ETSI (European Telecommunications and Standard Institute) standard of the ETS 300 092 series, which presents the requirements regarding the transmission of two numbers. The services are defined both in the basic ISDN subscription and in the ISDN system subscription.
The problem is that the terminal device has a limited capability of displaying numbers (typically a terminal device can display only one number). Moreover, users have different needs regarding presentation of numbers. Therefore, the telephone exchange system must be provided with a capability for selective subscriber number transmission. In addition, each subscriber must be able to control the transmission of subscriber numbers individually from the subscriber line. The object of the present invention is to eliminate the drawbacks described above. A specific object of the invention is to present a flexible and practical method that makes it easy to manage the subscriber number/numbers to be transmitted to the subscriber line of both the calling subscriber and the connected subscriber.
As for the features characteristic of the present invention, reference is made to the claims.
In the procedure of the invention, which is used in a telephone exchange system that may be e.g. an ISDN network comprising a number of telephone exchanges and the connections between them, a subscriber number is transmitted to a subscriber line involved in a call. A call can be set up between two subscriber lines or among several subscriber lines, in which case the call is a so-called conference call. Defined in the telephone exchange system are a number of subscribers together with the relevant subscriber data and a call is set up by means of terminal devices between subscriber lines, i.e. between the calling line and the called line. The called subscriber may also have activated a call transfer function, in which case the call will be connected between the calling subscriber line and the subscriber line assigned as receiver of transferred calls. The subscriber data comprise at least a subscriber number identifying the subscriber. The subscriber data are preferably stored in the telephone exchange system.
According to the invention, the stored subscriber data include information as to which number is to be transmitted to the subscriber line, i.e. data indicating whether the number to be transmitted to the subscriber line as the subscriber number of the other party of the call should be the subscriber number stored in the telephone exchange system, an unchecked subscriber number given by the subscriber, or both of these. Further, the procedure of the invention includes determining from the subscriber data which one or which ones of the subscriber numbers identifying the other party is to be transmitted to the subscriber line.
As compared with prior art, the present invention has the advantage that the procedure of the invention allows the subscriber to decide him/herself which one or which ones of the available subscriber numbers in his/her terminal device is/are to be presented as the subscriber number of the other party. In addition, in a telephone exchange system permitting the transmission of several subscriber numbers to a subscriber line, the invention also makes it possible to use a terminal device that is only capable of displaying one subscriber number, without contradiction regarding the number to be presented.
In a preferred embodiment, the number transmitted to the calling subscriber line as the other party""s subscriber number is a subscriber number given by the other party, the other party""s subscriber number stored in the subscriber data, or both. Further, the subscriber number of the calling subscriber line transmitted to the called subscriber line is a subscriber number given from the calling subscriber line, a subscriber number stored in the telephone exchange system, or both.
In a preferred embodiment, the procedure includes determining from the subscriber data during call setup or possibly at some other stage whether inhibition of number display has been activated for the subscriber line, in which case, if inhibition has been activated, no subscriber number is transmitted to the subscriber line. However, in certain special cases a situation may arise where the subscriber number is transmitted regardless of inhibition.
The information to be stored in the subscriber data regarding the number to be transmitted to the subscriber line can be controlled by means of MML (Man Machine Language) commands given in the telephone exchange system or the subscriber can give commands via his/her terminal device to update his/her subscriber data.
Moreover, in a Preferred embodiment, the transmission of the subscriber number of the calling and/or called subscriber line to the other party""s subscriber line can be disabled. In this case, the subscriber data includes information indicating that the subscriber number of the subscriber line is not to be transmitted to the other party""s subscriber line. Further, based on active inhibition present in the subscriber data, the other party""s telephone exchange is notified that the subscriber number is not to be presented. The inhibition can be set separately for each call or for all calls of the subscriber line.